In the initial phase of this ongoing program, approximately 500 ValveRegulated Lead Acid (VRLA) cells(both individual and 6 volt monoblocs) have been capacity tested and measurements made of conductance as well as conventional diagnostic parameters such as float voltage and specific gravity. Cells studied ranged from four to six years' service, from 200 to 1000 ampere-hour in size and included a group 0-7803-0779-8/92 $3.00 0 1992 IEEE
This paper presents data showing conductance aging of new cells and capacity/conductance aging of older cells. A presents data showing the comparative accuracy of several techniques for selection of a cell conductance value suitable for use in field determination of cell pass/fail conditions based on either capacity failures below 80% or below 50% of rated value. The accuracy of the various selected conductance values are determined by actual comparison to cell by cell capacity/conductance data. This data represents 192 cells of 1000 AH (Ampere Hour) size in 48 volt telecom use and 96 cells of 600 AH size in 24 volt strings in another type of telecom usage. The data presented should allow the user to select a technique which appears most suitable to his needs and capabilities. lntroduct ion/Background : During the last several years, the authors have presented the results of a series of studies showing the relationship between measured VRLA (Valve Regulated Lead Acid) cell capacity and measured cell conductance. These papers included capacity/conductance data on several thousand cells and monoblocs, ranging from 25 to 1000 ampere-hours in capacity and representing the products of five different battery manufacturers 2r3v4. These results have documented the close correlation between measured cell capacity and measured cell conductance. More recent publications have demonstrated the initial application of techniques utilizing these conductance values to detect individual cell capacity failures (less than 80% of rating), with an accuracy generally exceeding ninety percent 4p6p8p9.Those studies have all enjoyed the benefit of actual capacity test data obtained in conjunction with conductance values and hence may be considered as the first step in confirming the utility of the conductance test in detecting low capacity VRLA cells.For the user to utilize this technology effectively in the maintenance and surveillance of the condition of his battery plant, he must have available some type of "signature" information for the specific type of cell involved in order to determine the appropriate conductance value corresponding to the capacity failure criteria (usually 804/) at which some remedial action must be taken.In this paper, the authors present several techniques for obtaining these "signature" conductance values, explain their derivation and their significance, demonstrate the procedures involved in their utilization and present and analyze typical predictive results obtained.
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